The present invention relates to disc drive data storage systems and, more particularly, to a method of applying a serial number or other information pattern to a surface of a disc head slider.
Disc drives of the xe2x80x9cWinchester typexe2x80x9d are well known in the industry. Such drives use rigid discs coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor which causes the discs to spin and the surfaces of the discs to pass under respective head gimbal assemblies (HGAs). The HGAs carry transducers which write information to and read information from the disc surface. An actuator mechanism moves the HGAs from track to track across the surface of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a load beam for each HGA. The load beam provides a preload force which presses the HGA toward the disc surface.
The HGA includes a hydrodynamic (e.g. air) bearing slider and a gimbal. The gimbal is positioned between the slider and the load beam to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc. The slider includes a slider body having a leading edge, a trailing edge and an air bearing surface which faces the disc surface. As the disc rotates, the disc drags air under the slider along the air bearing surface, which creates a hydrodynamic lifting force that causes the slider to lift and fly above the disc surface. The transducer is typically mounted at or near the trailing edge of the slider.
Air bearing disc head sliders are formed from a substrate known as a wafer. A matrix of transducers is applied to a top surface of the wafer and then the wafer is sliced into a plurality of bars. Each bar includes a plurality of individual slider bodies, with each body having a corresponding transducer. Each bar is then diced into individual slider bodies.
It is often desired to apply a serial number or some other useful information to each slider body. Serial numbers have been applied to the leading edges of slider bodies by a laser scribing process. During the laser scribing process, a beam of laser light is directed toward the slider substrate material. The beam removes material in a pattern corresponding to the serial number. A disadvantage of the laser scribing process is that the removed material often redeposits on the slider substrate, which creates contamination. Furthermore, the legibility of the applied serial number is occasionally questionable.
The method of applying an information pattern to a disc head slider according to the present invention includes applying a metal film to a surface on the slider substrate and then laser scribing the information pattern into the metal film.
In one embodiment, the information pattern includes a serial number for the particular slider body to which the serial number is applied. The step of laser scribing preferably ablates material to a depth which is equal to the thickness of the metal film, with little or no substrate material being removed. In another embodiment, the step of laser scribing ablates material to a depth which is less than the thickness of the metal film. In yet another embodiment, material is removed to a depth which is greater than the thickness of the metal film such that the serial number is scribed through the metal film and into the surface of the slider substrate. The metal film may then be removed, leaving the serial number in the exposed substrate surface.
The metal film can be applied by sputtering, plating, chemical vapor deposition or other means for applying a thin metal film. The thickness of the metal can be monolayers to several microns. The steps of applying the metal film and the step of laser scribing can be performed at a wafer level, a bar level, or a slider level. In a preferred embodiment, the metal film and identification pattern are applied to a leading edge of each slider body, at the wafer level.